2.4 Extraction of metals (AS)
Principles of metal extraction
Metals are found in ores, usually as oxides or sulfides.
Sulfide ores are usually converted into oxides by roasting in air
Environmental problems associated with the conversion of sulfides into oxides and also that the sulfur dioxide produced can be used to manufacture sulfuric acid.
Extraction of metals involves reduction
Carbon and carbon monoxide are cheap and effective reducing agents that are used in the extraction of iron, manganese and copper (reduction equations and conditions only)
Carbon reduction is not used for extraction of titanium, aluminium and tungsten (reasons why)
Aluminium is manufactured from purified bauxite (energy considerations, electrode equations and conditions only)
Titanium is extracted from TiO2 via TiCl4 (equations and conditions only: either Na or Mg as a reducing agent)
Tungsten is extracted from WO3 by reduction with hydrogen (equation, conditions and risks only)
Environmental aspects of metal extraction
Environmental and economic advantages and disadvantages of recycling scrap metals compared with the extraction of metals
Environmental advantages of using scrap iron to extract copper from aqueous solutions compared with the high-temperature carbon reduction of copper oxide
Know that the usual source of such aqueous solutions is low grade ore